[llvm] [AArch64] Use a load instead of a store for inline stack probes (PR #170855)

[Momchil Velikov via llvm-commits]

momchil-velikov wrote:

LGTM (we already used load into `xzr` as a probe in one place).

I would suggest to expand the description into something like

> Frequently, when big buffers are put on the stack we end up with multiple virtual pages COW-mapped to single physical zero page. Stack probes would unnecessarily trigger a COW on such pages. Avoid this by using loads into the `XZR`.


https://github.com/llvm/llvm-project/pull/170855